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1fca994c7b
Before this change, if a read executor had just enough targets to achieve query's CL, and there was a connection drop (e.g. node failure), the read executor waited for the entire request timeout to give drivers time to execute a speculative read in a meantime. Such behavior don't work well when a very long query timeout (e.g. 1800s) is set, because the unfinished request blocks topology changes. This change implements a mechanism to thrown a new read_failure_exception_with_timeout in the aforementioned scenario. The exception is caught by CQL server which conducts the waiting, after ERM is released. The new exception inherits from read_failure_exception, because layers that don't catch the exception (such as mapreduce service) should handle the exception just a regular read_failure. However, when CQL server catch the exception, it returns read_timeout_exception to the client because after additional waiting such an error message is more appropriate (read_timeout_exception was also returned before this change was introduced). This change: - Add new read_failure_exception_with_timeout exception - Add throw of read_failure_exception_with_timeout in storage_proxy - Add abort_source to CQL server, as well as to_stop() method for the correct abort handling - Add sleep in CQL server when the new exception is caught Refs #21831